Carver said he personally performed seven autopsies and those children had between three and 11 wounds each. Two were shot at close range, the others at a distance.

Asked whether they suffered, he grimly replied, “Not for very long.”

He said he will perform an autopsy Sunday on the suspected gunman, Adam Lanza, 20, who is believed to have killed himself. He will also do an autopsy on Lanza’s mother, Nancy Lanza, 52, who was found dead in her Newtown home.

President Barack Obama will travel to Newtown on Sunday to meet with the victims' families and thank first responders, the White House announced Saturday night. The president will also speak at an interfaith vigil for families of the victims as well as families from Sandy Hook Elementary School.

The motive for the mass killing, the second-deadliest school shooting in U.S. history, was unknown.

“We’ve been doing everything we need to do to peel back the onion, layer by layer, and get more information,” Connecticut State Police Lt. Paul Vance said earlier.

"Our investigators at the crime scene ... did produce some very good evidence in this investigation that our investigators will be able to use in, hopefully, painting the complete picture as to how - and more importantly why - this occurred.”

Connecticut Chief Medical Examiner H. Wayne Carver provides an update to the media after he and his team examined the victims' bodies at Sandy Hook Elementary School in Newtown following Friday's shootings.

Four doctors and 10 technicians, plus a college student working her first day with the medical examiner’s office, toiled into Friday night to identify the victims.

They took photos of their faces and then showed the pictures to families of the 12 girls and eight boys, all first graders. “It’s easier on the families when you do this,” Carver said.

He said that he managed to maintain professional composure during the work, but it was a challenge.

“I’ve been at this for a third of a century and my sensibility may not be the average man’s, but this is probably the worst I’ve seen,” Carver said.

Newtown’s first selectman, Patricia Llodra, pleaded for privacy for the grieving families, each assigned their own trooper.

“We are a strong and caring place. We will find a way to heal so that all of our residents young and old find peace,” Llodra said. Please know that we have suffered a terrible loss and we need your respect on this terrible journey.”

Although the bodies were removed from the suburban hilltop school, authorities said it would take at least two more days for investigators to finish combing over the crime scene.

Police have determined that the gunman was not buzzed into Sandy Hook, where he was once a student.

“He forced his way into the school,” Vance said. He did not provide specifics and said that broken windows at the school may have been shattered by police who responded to the emergency.

In the confusing aftermath of the shooting, law-enforcement sources gave out conflicting information about what transpired.

Several media organizations, relying on information provided by law-enforcement sources, initially reported that the shooter had been identified as Lanza’s older brother. Officials later corrected that mistake.

There was also conflicting information about what type of weapons Lanza had.

At one point, law enforcement officials told NBC News that Lanza had four handguns while he stalked the halls of Sandy Hook, but that could not be confirmed. It appears he carried at least two 9mm handguns, in addition to the rifle, which was the primary weapon.

Officials also told NBC News that Lanza unsuccessfully tried to buy a rifle at a Dick’s Sporting Goods store in Danbury three days before the slaughter, but later said they could not confirm the report, which was based on tips from members of the public.

Investigators and former classmates of Connecticut school shooter Adam Lanza say he was bright, but extremely shy and remote. NBC's Pete Williams reports.

Police provided little information about the shooter’s state of mind. Lanza’s brother told police the gunman had a history of mental problems, though a classmate from Newtown High School recalled him as a generally happy person.

“We would hang out, and he was a good kid,” Joshua Milas, who had not seen Lanza in a few years, told The Associated Press. “He was probably one of the smartest kids I know. He was probably a genius.”

Newtown Police Lt. George Sinko said the entire town of 27,000 – a New England bedroom community some 60 miles from New York City and known for its good schools – was reeling.

“We never thought this would happen here,” Sinko said. “Our hearts are broken for the families of these victims.”